A blog by Catharine Ellis

I first met Sarah Bellos of Stony Creek Colors in 2016 when she spoke at the Growing Color Symposium at the NC Arboretum in Asheville. She presented her vision for growing and extracting indigo in Tennessee. Her goal was to introduce natural indigo to the denim industry, which is currently a huge consumer of synthetic indigo (a serious source of environmental pollution). She was partnering with Tennessee farmers who had previously grown tobacco and planned to process indigo dye locally.

Air drying of traditional burley tobacco in TNSome Tennessee grown tobacco is cured by smoking with wood fire

I must admit that I was somewhat skeptical. The project seemed too big and too optimistic. I didn’t know anyone who had successfully grown indigo dye plants on the scale that she described.Most dye plants are grown for commercial purposes in India or South America, where the price of labor is far less. Indigo was grown in the Southeast coastal regions of South Carolina and Georgia in the 17th and 18th centuries but, to my knowledge, has not been grown commercially in North America since that time.

On a recent visit to Stony Creek near Nashville, TN I was very pleasantly surprised and now believe that they are truly on the way to something successful and very much needed. I’d like to tell you why I believe this.

The first place visited was the “test farm”.I had envisioned a small plot of Persicaria tinctoria but was amazed to find that the test farm was a densely planted, multiple acre farm tract where several strains of Persicaria tinctoria are growing next to the tropical varieties of indigo(Indigofera suffruticosa and Indigofera tinctoria).

Tropical indigo plants (Indigofera suffruticosa), harvested and continuing to grow in foreground, not yet harvested in backgroundSarah in the test field, where several varieties of indigo are grownPersicaria tinctoria, in bloom

Why grow so many different types of plants? Sarah and her staff are constantly asking questions and testing: Which varieties can be sown directly in the ground? Which need to be started in the greenhouse? Some strains bloom more readily than others (great for seed production but not so good for indigo production). Which plants can be dried for future extraction? What is the indigotin content vs. the biomass of the plants? Which can be harvested most efficiently?

I believe that the Stony Creek team is concluding that there is wisdom in growing more than one variety of indigo.The farmers are currently growing many acres of indigo for pigment extraction. All farms are within a reasonable drive to the factory, as it is necessary to process the indigo leaves quickly.

The next stop was Stony Creek’s lab.Walking in the door I saw that the dye chemist, Summer Arrowood, was pulling leaves from Persicaria tinctoria stems that had been harvested earlier that morning. She was weighing those leaves and recording the leaf-to-stem ratio. Next, individual bags of leaves (from very specific plants in very carefully identified locations at the test farm) were processed to extract the indigo pigment. I sensed that this was part of each day’s work at the lab. The leaves were soaked in hot water, the liquid was pumped into vessels for aeration, the paste was allowed to settle and then filtered. Several hours later, each batch of leaves had produced a small amount of indigo pigment. These were tested, labelled and stored for future reference. They report that their indigo contains 25-35% indigotin which is a very concentrated output.

Vessels for test extractions of pigment. Sarah is holding the piping used for introducing oxygen into the indigo extraction in order to precipitate the pigment.Filtering of test pigmentPigment extracted from test extractionsEach sample batch of pigment is carefully labeled for reference

Stony Creek is experimenting with extraction from dried plant material in order to extend the production season.

The production factory is located in a county-owned, former tobacco factory and leased by Stony Creek.Here, 20,000 pounds of indigo plant material can be processed in a single batch. The factory is set up with modern equipment, carefully laid out, and efficient. Stony Creek precipitates indigo pigment without the use of lime (calcium hydroxide). When too much lime is used during the process, it will remain in the indigo pigment and skew the weight of anyavailable indigotin. The extraction without lime is one of the reasons the pigment has such high levels of indigotin. The pigment paste is carefully filtered using processes that Stony Creek has developed specifically for indigo.

Truck trailers used for indigo harvest and initial steeping of plants.Water that has been collected from the root and heated in solar tanks is used for extracting the indigo.Stainless tanks are used for aerating the indigo. Stony Creek has recently installed two additional tanks.Plastic tanks are used for settling of the indigo paste.All indigo paste settles to the very bottom of the tanks. The remainder is waste water, that is properly neutralized before discarding.

How has Stony Creek come this far so quickly? Sarah Bellos has an academic background and experience in natural resources management and sustainable agriculture. She is a self-taught natural dyer; she and her sisters operated a dye business for several years under the name Artisan Natural Dyeworks. Stony Creek employs skilled and smart people, who know chemistry, plants, agriculture, and manufacturing. The farmers, who grow the indigo, are benefiting from a cash crop that has the potential to replace the tobacco that grew here for so long. Stony Creek is currently selling indigo paste to denim producers and they are able to test/replicate the warp dyeing process used by the denim industry in their lab. Sarah had a vision to produce natural indigo and they are making it a reality.

This chart says it all!

At a time when some of us are unsure if we are purchasing natural indigo or synthetic indigo (or a mix of both) Stony Creek is a beacon of light. I have used their indigo and it is excellent. Of course I will purchase my indigo from them! I will encourage other dyers to do the same.

Stony Creek is NOT yet set up for visitors. Right now, they need to focus on the work at hand and continue to develop their current products: indigo, black walnut paste extract (that really works!), and a madder extract paste (currently from Rubia tinctorium roots grown in India until their own roots are ready for harvest).

After this year’s indigo harvest they plan to move the lab to the factory location and at some time in the future will be able to offer workshops onsite. I hope that you will consider helping to grow this promising endeavor by trying out their excellent indigo, and other extracts available for order online at their website. Other dye suppliers are also beginning to carry and sell Stony Creek Indigo.

The day we visited the factory, there was no indigo being processed. It had rained the day before and the indigo plants cannot be harvested when wet; this whole process is tied closely to the land. Before we left in the afternoon, the truck and trailer had left for the fields, ready to be loaded with indigo plants early the next morning.

Yesterday I received a phone call from Schiffer Publications – the publisher of Joy’s and my upcoming natural dye book.

I am sorry to report that the release date, originally projected for the end of October, has been delayed until late January.

Why the delay?

Schiffer is taking great pains to be sure that all color reproduction is exact and precise. The book is illustrated with photos of actual samples from my dye tests. Our goal was to share some of the hundreds of samples that I have done, comparing the use of different mordants, tannins, dye treatments, times in the dyebath, etc. Many of the variations are subtle – but the differences are important.

Careful color adjustments have been made to the digital images in Art & Science of Natural Dye to ensure that the dye colorsreproduce as accurately as possible throughthe print process. Color proofs arereviewed and compared to the actual dye samples as part of this process.

Yes, it will be delayed, but the color will be the best possible printed reproduction and I’m very happy about that. It’s good to be working with a publisher that really cares about these “small” details – they are really not small at all. Below is just a small hint of what will be included.

black walnut on wool

cochineal variations on silk

pomegranate dye variations

comparison of mordants on cellulose

printing of ferrous acetate with different tannins and dye

cross dyeing of wool and cotton

use of iron post mordant

various tannins with mordants and dye

indigo print

indigo discharge

I know that many of you have pre-ordered the book and are anxiously awaiting it. Joy and I appreciate the vote of confidence and are sorry for the delay.

I can suggest a great thing to do while you’re waiting:

Yesterday, on a long drive back home from New England, I finally had the chance to listen to a lecture given by Michel Garcia and available as a Maiwa Podcast. It’s title is Field Notes in the Color Garden, parts 1 & 2. It’s a long, wonderful, rambling lecture that Michel gave in 2015 and Maiwa uploaded as a podcast this year.It has given me much to think about in regards to dye plants, resource books, investigation, and the human scale of natural dye.

And keep dyeing!

It’s still less than a year since Joy and I turned in the manuscript and images to the publisher. My learning has not stopped and once the book is released, I look forward to sharing some of the things I’ve continued to work on and learn about since we sent the manuscript away.“Stay tuned”.

I have always enjoyed how the goldenrod grows and blooms alongside the purple asters – a beautiful combination of complimentary colors.Goldenrod (Solidago sp.) is a member of the aster family. There are many solidago species native to North America, and they can also be found in other parts of the world.

Goldenrod flowers, gathered in western North Carolina

Goldenrod and New England Asters, photo from Denver Botanical Gardens

Goldenrod and thistles, Newfoundland, CA

Is goldenrod a good source of dye? Yes, but with reservations.

Though it is not one of the “classical” dyes, and it’s lightfastness does not match that of weld, it was used as a locally available dye in North American and Europe. Dominique Cardon (Natural Dyes: Sources, Tradition, Technology, and Science) writes about goldenrod’s historical use, along with weld and Persian berries, to dye the yellow hats the Jews were required to wear in the south of France in the 13th century.

I’ve always readthat goldenrod does NOT dry well for future use – so I never tried to dry it. I can accept the fact that some dyes deteriorate in the drying process. Black walnut hulls are a good example.

A couple years ago I was teaching a class here in Asheville, NC on dyes that could be sourced from the local food co-op. I used dried goldenrod plant material, as it is used medicinally. It resulted in very good color. So I began to wonder….. CAN A GOOD DYE BE OBTAINED FROM DRIED GOLDENROD?

It’s one thing to read a statement about a plant – it’s another thing to know and understand that statement. Ihad never tried to dry goldenrod. This year I finally got around to doing my own testing.

I gathered fresh goldenrod, and used that to dye aluminum mordanted wool, silk, and cotton. There are many yellow dyes in goldenrod and they may include quercitron, isoquercitron, kaempferol, astragalin, isorhamnetin. Since the dyes in goldenrod are primarily flavonols, a mordant is required.

I dried goldenrod from that same harvest. Plants were hung upside down in a dry space with plenty of air flow. Only the flowering heads were used as a source of dye. I was able to accurately determine the weight of the plant before and after drying. 300 grams of fresh goldenrod flowers resulted in 100 grams of dry flowers.

100 grams of dried flowers (left) and 300 grams fresh flowers (right)

I dyed with fresh goldenrod at 300% w.o.f, while the dried was used at 100% w.o.f. Because I knew the weight before and after drying, I was confident that I was using the same amount of dye, whether it was fresh or dry plant material.

The results: The dyes seem not to have suffered from the drying process. Careful drying is likely a key element. So yes, I will dry some goldenrod and I will complete lightfastness tests on all three fibers. The goldenrod will not replace the weld that I grow and dry each year, Weld will always be my primary yellow dye as that has proven to be the best, and most lightfast yellow dye. But it is good to know a bit more about the dyes from plants available in my neighborhood.

Thus far I have used only the flower heads for dyeing. Maybe next year I’ll experiment with the stems and leaves from the entire plant.

I’ve used Aleppo galls (either ground or extract) for years as my preferred tannin.They were recommended to me as being high in tannin and are readily available. Gall is a source of colorless, gallic tannin. I’ve done many tests comparing the Aleppo gall to tannins, such as sumac (from local leaves), myrobalan, tea, and many others but I had never compared different varieties of oak galls.

First of all, what is an oak gall?They are sometimes called “oak apples” and are small, round growths of plant tissue produced by the oak tree in response to the infestation and larvae of a wasp.There are many different species of wasps as well as oak trees. As a result, the galls from each of these is different. The Aleppo gall nut (Quercus infectoria) is hard and dense but can be ground to producefine particles.

A friend from Missouri gave me a jar of her local gall nuts. She lives in a forest of white oak (Quercus alba) and gathers the galls when they fall to the ground. These galls have a smoother surfacethan the Aleppo but are just as hard and dense.

Recently I was in New England and was able to gather galls from the scarlet oak variety (Quercus cocinea). These are larger, very light in weight, and seemingly hollow. As a child, we referred to them as “puff balls”.

White oak galls from Missouri

Scarlet oak galls from New England

Scarlet oak galls

I wanted to know something about the tannin quantity of these various galls and if they could be used interchangeably for dyeing applications.They were applied to cotton fabric prior to mordant and dye. I used each of the tannins at 10% weight of fiber, which is the standard amount I use of gall nut extract.

1 gram of each gall source

The whole galls were ground with a small spice grinder, and further crushed using a mortar and pestle. Those from the White and Aleppo oaks broke down into fine granules, while the Scarlet oak variety was impossible to grind as fine, as the insides were truly “puffy” and “spongy”. Each of the ground gall varieties and the extract were put into warm water, using separate beakers for each, along with the cotton cloth.They sat at room temperature for 1 hour before the mordant was applied.

white oak gall, ground

scarlet oak gall, ground

Aleppo oak gall, ground

Aleppo extract (from Maiwa)

Left to right: white oak, scarlet oak, ground aleppo, Aleppo extract

I took a portion of the samples with the tannin application and put them into a weak iron bath. When tannin and iron combine a dark grey or black will result. The shade of grey is an indication of the amount of tannin present. The Aleppo gall nuts, in either the ground or extract form, resulted in much deeper shades of grey than either the white or the red oak varieties. The large pieces from the scarlet oak resulted in a very uneven application of tannin. When the iron was applied, the surface was very splotchy and irregular.

TOP: Tannin only. Although the galls appear to have colorants, an insignificant amount of color attached to the textile. MIDDLE: with weak iron applicaton. BOTTOM: sample shows the uneven application of the scarlet oak gall.

The rest of the samples were then mordanted and subsequently dyed with both weld and madder. The amount of tannin has a direct effect on the amount of mordant that can attach to the textile, and the depth of dye color obtained is a direct reflection of the amount of mordant present. Based on the iron applications, I was surprised at the depth of the color obtained with all of the gall varieties. Although the dye color obtained from the white and scarlet oaks is lighter than the Aleppo, there is still significant color attached.

When using tannin prior to mordanting, it is likely that increasing the amount of gall from the white or scarlet oaks would increase the amount of mordant that attaches and thus the depth of dye color.

Locally harvested galls, when available, are an opportunity to use the local resources and achieve acceptable results.

A life of natural dyeing knows no bounds. Each year I am thrilled and delighted to increase my knowledge and understanding of dyes and process.

This year, I was privileged to participate in the harvesting of indigo and the extraction of pigment on the island ofOkinawa, Japan.

The Okinawa farm has been producing indigo for many years, as evidenced by the large, round concert vessels imbedded in the ground. The vessels are used for extraction of pigment.Smaller square vessels, also in the ground, are used for the storage of the indigo paste pigment.

The indigo harvest and extraction is currently being done by a young couple, Takashi and Kitta Sawano. They have been extracting pigment here since 2012.He is a dyer. She designs and makes beautiful, naturally dyed cotton garments in a studio located in northern Okinawa. The process of harvest and extraction requires many helping hands and there were a number of friends and artisans who came to get their hands dirty and participate.

The variety of indigo is Strobilanthes cusia. It looks similar to polygonum tinctorium but this variety requires a hotter climate and has a greater content of indigotin. Even the stems of the plants contain indigo. Eight different harvests are made during the summer season to extract pigment from all the indigo plants.

It was pouring rain the morning we arrived to harvest. I was given a small scythe and some white ropes. I felt somewhat prepared for the cutting and tying process since this is the same approach that we used last summer when harvesting Polygonum tinctorium at Rowland Ricketts studio/farm. Everything else about the process was different, since Rowland uses his indigo to compost the leaves for sukumo.

Field of indigo

Weighing the indigo plants

Rinsing the bundles of mud and debris

The goal was to collect 400 kilos of indigo plant (leaves and stems). Each bundle was weighed and the weight of the wet leaves was taken into consideration. The plants were then tossed into one of the large round vessels that was already filled with water. A porous round tarp had been placed over the surface and the plants went on top of that. The indigo plants were weighted down with wire mesh, boards and rocks to ensure full immersion.The plants were left to soak for the next 24 hours.

Adding the indigo plants

Weighting the plants

Wire mesh was added to insure full and even immersion

Every last leaf is valuable

Many hands….

On the next day, we observed that some fermentation was beginning and measured the pH.

Fermentation just beginning

On the the third day, the fermentation was very active. The plant material was lifted out of the vessel (with the help of a small tractor). Lime was added. The amount of lime was carefully calculated as too much lime will result in an inferior pigment. The indigo extraction was aerated for 45 minutes using long rods with a small paddle affixed to the end. The shape of the vessel made this a very efficient operation.

Active fermentation on the third day

Removing the leaves

Removing the weights

Aerating

Aeration is complete

Adding lime

The introduction of oxygen through aeration caused the indigo pigment to precipitate to the bottom of the vessel. Once the excess water was pumped off the surface, the paste pigment could be pumped into a storage container, where a more concentrated pigment will settle to the bottom over the next few weeks.

Pumping off the surface water

Pumping pigment into the storage tank

Removing every last bit of pigment

Hisako Sumi and Kitta Sawano, both dressed in indigo

I purchase indigo for use in my own dye vats. Most of it has come from India but I am currently using indigo grown right here in the U.S. at Stoney Creek Colors. This experience has given me a new appreciation and understanding of the cycle “grow, extract, dye” and a deep respect for those who participate in the entire process. My thanks go to Hisako SUMI, who has participated in this indigo harvest for the last number of years and invited me to attend – in the spirit of understanding and sharing.

Cross dyeing: A method of coloring fabrics made from more than one kind of fiber. Each fiber in a fabric designed for cross–dyeing takes a specific dye in a different color or in variations of a color.

… The Fabric Dictionary

As a weaver, I often construct my own textiles before they are dyed. I choose warp yarns,weft yarns, and then make decisions about how they are going to be fit together. When a fabric is constructed using both protein and cellulose fibers, some dyes can be made to attach only to the wool. Direct dyes, such as black walnut husks, are a great example. When used on wool or silk, without the use of a mordant, those fibers will dye a deep brown, while any cotton used in the construction of the textile will only be lightly stained or absorb no dye at all.

This allows me to weave fabrics in white or natural, and then apply the color afterwards, using resists to incorporate design and create layers of color.

Wool, cotton, and silk yarns in the warp.

When indigo in used in combination with a direct dye, the cotton will only absorb the indigo blue.The protein fiber will absorb some of the indigo, but it is initially a much lighter blue. When overdyed with a direct dye, only the protein fibers will accept that direct dye.

This is an approach I have taken to dyeing my woven textiles for a number of years, ever since I was inspired by a Moroccan belt fabric that used acid dyes to achieve the effects of cross dyeing.

Belt from northern Morocco, woven in wool and cotton, dyed with acid dyes.

When I began working with natural dyes and wanted to do cross dyeing, I was initially limited to the use of direct dyes, such as black walnut husks, lichens or other dyes that did not require a mordant. Ifa mordant is used, both fibers will dye to some extent.Then Michel Garcia introduced me to the concept of one-bath dyeing.This is where tannins and acid are used to attach some dyes to a protein, while the cellulose fibers do not dye at all. In effect, the dyes behave like acid dyes. No mordant is required when applying dyes with this process.

Indigo dye on cotton and wool fabric. The cotton is a deep blue, while the wool is very light, although they were dyed in the same bath.

Top: black walnut dye only on wool and cotton. Bottom: indigo and black walnut on wool and cotton , with resists

Wool and cotton, dyed with indigo and alkanet

wool and cotton, dyed with indigo and madder

Fabric woven of cotton and wool. Clamped resist, indigo dyed.

Same fabric, overdyed with madder, using the one-bath acid dye approach

But not everyone is a weaver! Next month I will be teaching natural dyeing for knitters at the first Knitting Getaway at Shakerag Workshops . In preparation, I have been knitting samples that incorporate both wool and cotton. I have added resists, and dyed with combinations of indigo and one-bath acid dyes. This concept can also be applied to knitting yarns that incorporate both wool and cotton.

Knit samples, using wool and cotton yarns, and dyed with indigo, cochineal, and rhubarb root.

It is challenging to identify commercially available fabrics for cross dyeing. I have had fabrics specially woven of wool and cotton for the class that I’ll be teaching at the 11th International Shibori Symposium in Nagoya, Japan. Space is still available in the workshop right now!

Silk and rayon, dyed with indigo and rhubarbLinen and silk, dyed with indigo + cochineal rhubarb, madder, and madder.

And on another exciting note: The Art and Science of Natural Dye will be published by Schiffer Publishers in the fall and is now available for pre-order from Schiffer or Amazon. In fact, I just finished the last of the copy edits today!

I often receive questions about indigo dye that fades very quickly on a textile. When I ask the dyer how long the textile was immersed in the vat the response is usually “1 or 2 minutes”. That is not enough time! Each immersion in the vat needs to be long enough to permit the indigo to penetrate into the fiber: at least 10-15 minutes. Otherwise the dye simply sits on the surface of the textile, making it susceptible to fading and rubbing off.

Recently, I completed a series of tests in which I experimented with much longer immersions in the vat. Immersion times in the vat ranged from 20 minutes to 20 hours. A longer dip encouraged more dye to penetrate the fibers. The results are worth observing and discussing. All samples were neutralized in a vinegar/water solution and “boiled” to finish and remove excess dye.

Indigo on cotton, silk, and wool, each with a single dip in the vat

The most common method of achieving dark colors with indigo is multiple successive dips in the vat and there are definitely some advantages to building color in this way. Any unevenness of the dye will level out as the textile is immersed multiple times. This is especially important when dyeing large textiles in a small vat. (This is the reason why larger vats are better suited when dyeing large textiles; allowing the dye to reach more of the textile surface) If the vat is large enough that the textile can be immersed and exposed evenly to the dye, longer immersion times may be a practical approach.

Indigo on cotton, silk, and wool with multiple (1-6) 15 minute dipsFabric woven of wool and cotton yarns. After a single 20-minute immersion, the cotton fiber is darker. After 2 hours, both fibers are close to the same color. After 18 hours, the wool has absorbed a great deal more indigo while the cotton has maxed out. Multiple dips in the vat are required to achieve very dark blues on cotton.

My usual approach to dyeing textiles is using woven shibori. The textile is gathered with the woven “stitching” threads, making a compact “package”, and exposing the outside pleats of the textile to the dye uniformly.

Cotton, woven shibori, multiple indigo dips

Lately I have been experimenting with itajimi shibori (folded and clamped resists), where many layers of cloth might be folded multiple times. When using mordant dyes or fiber reactive dyes, the dye usually penetrates through the layers. When dyeing with indigo (10-20 minute immersions), the dye fails to penetrate beyond the outside layer and into the cloth within the folds, despite multiple immersions. When the immersion time was increased to 24 hours the dye penetrated ALL the layers – like magic. More time in the vat allowed complete penetration of dye throughout the textile.

Cotton, itajimi shibori sample, multiple immersions (20 minutes each)

Cotton, itajimi shibori sample, single immersion, (24 hours)

Lightfast tests were performed on all samples dyed with extended times in the vat by exposing 1/2 of the samples to four weeks in a window with direct sunlight.

lightfast test: cotton (4 weeks exposure to direct sunlight)

lightfast test: wool (right side exposed to sun 4 weeks)

lightfast test: silk (right side exposed to sun 4 weeks)

Note: When dyeing protein fibers, care must be taken with the pH of the vat, as the fibers can be damaged by long exposure if the pH is too high. Ideal pH for protein is 9.5-10.

The North Carolina Arboretum is hosting the second Growing Color Symposium on March 8, 2018. Michel Garcia will be our keynote speaker. Join us if you can!